Electronic apparatus and method of manufacturing thereof

ABSTRACT

In an electronic apparatus such as a portable computer comprising an electronic apparatus housing having boss portions, projecting portions are formed at locations where boss portions are to be formed. In addition, a boss separate body is provided which has an engaging hole therein and is to be attached to each of the projecting portions to form the boss portions.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a Continuation of Application No. PCT/JP99/01763, filed Apr. 2, 1999.

[0002] This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 10-173020, filed Jun. 19, 1998, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0003] This invention relates to a housing for electronic apparatuses such as personal computers, in particular, a boss structure of an electronic apparatus housing.

[0004] Recently, a housing mainly using a magnesium alloy as material is adopted as an electronic apparatus housing formed of light metal. The alloy is molded by a die-cast method and a thixotropy method. Although these molding methods are different in the device structure, they are performed under the condition where the alloy which has been molten at 580-750° C. is injected and molded in a mold having a temperature of 100-350° C.

[0005]FIG. 1 shows a structure of a conventional electronic apparatus housing. In an electronic apparatus housing 1, molten metal is introduced from a sprue 2 which is a part for introducing molten metal into a molding device (in FIG. 1, explanation is made by using parts corresponding to the form of the electronic apparatus housing immediately after molding), and passed through a runner 3 so that the molten metal is introduced into a desired mold. The introduced molten metal extends through the whole cavity 4 to reach an air vent 5. A basin 6 is further connected to the air vent 5. Therefore, when the molten metal is introduced from the sprue 2, air can be released outside through the air vent 5, and thereby the housing can be formed in the state where no void exists in the housing.

[0006] A plurality of bosses 7 are provided on the electronic apparatus housing 1 in order to mount various electronic circuits or the like on the housing. The bosses 7 are formed as one piece with a bottom portion of the electronic apparatus housing 1 by pouring the molten metal in concave hole portions formed in the mold. Further, the bosses 7 are provided so as to project from the bottom portion of the electronic apparatus housing 1.

[0007] Further, screw holes 8 are formed at the bosses 7, which make it possible to engage an electronic circuit and other various parts by screw.

[0008] In the meantime, the hole portions which are formed in the mold in order to form the bosses 7 are formed in the form of a deep groove in a direction perpendicular to a direction of flow of the molten metal along the cavity 4 of the mold, so as to conform to the form of the bosses 7 of the electronic apparatus housing 1. In this case, though the molten metal easily flows in a direction along the flow of the molten metal of the cavity 4, the holes are formed perpendicular to the cavity 4, and therefore the molten metal does not easily flow into the holes as the form of the holes is made deeper.

[0009] Specifically, since the temperature of the mold is lower than the temperature of the molten metal, when the molten metal comes into contact with an internal wall of the mold, solidification of the molten metal is quickly started. However, when the holes are formed deeply, solidification of the molten metal is started before the molten metal flows into the end portion side of the holes. Therefore, a portion into which the molten metal is not filled is generated, and there are cases where the bosses 7 are not formed in a desired form, or do not have a desired height.

[0010] In the case where such bosses 7 are formed, screw holes 8 cannot be formed inside the bosses 7 in a good state, and there can be produced an inconvenience that an electronic circuit and other various parts cannot be fixed in a good state.

BRIEF SUMMARY OF THE INVENTION

[0011] The present invention has been made on the basis of the above circumstances. The object of the invention is to provide an electronic apparatus having a housing which includes no non-filled portion and can form a boss form in a good state, and a method of manufacturing thereof.

[0012] In one preferred embodiment, an electronic apparatus of the present invention comprises a housing, and a boss member formed as a separate piece from the housing and mounted on the housing to form a boss portion.

[0013] Further, a method of manufacturing an electronic apparatus of the present invention is a method of manufacturing an electronic apparatus having a housing with a boss portion of a predetermined height, comprising the steps of: a housing forming step for forming the housing introducing molten metal into a mold device, the housing having a projecting portion at a location where the boss portion is to be formed, and the housing constituting portions other than the boss portion of the housing; and a boss portion forming step for forming the boss portion by fixedly engaging a boss member, which is to constitute the boss portion, with the projecting portion.

[0014] Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0015] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.

[0016]FIG. 1 is a perspective view showing a form of an electronic apparatus housing concerning conventional art;

[0017]FIG. 2 is a perspective view showing a structure of a portable computer used as an electronic apparatus concerning an embodiment of the present invention;

[0018]FIG. 3 is a diagram showing a flow chart of a method of manufacturing the electronic apparatus;

[0019]FIG. 4 is a perspective view showing a form of an electronic apparatus housing used for the electronic apparatus;

[0020]FIG. 5 is a side cross-sectional view showing a state of a boss portion and around the boss portion of the electronic apparatus; and

[0021]FIG. 6 is a perspective view showing a form of a mold device.

DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment of the present invention will now be described on the basis of FIGS. 2 to 6.

[0023]FIG. 2 is an outside drawing showing a form of a portable computer 10 such as a notebook computer used as a kind of electronic apparatus. In FIG. 2, the portable computer 10 comprises a computer main body 11, and a display unit 12 which is rotatably supported on the computer main body 11. Further, the computer main body 11 comprises a housing 13, and the housing 13 has a structure wherein a lower housing 14 and an upper housing 15 are joined by screw or the like. However, the structure for joining the lower housing 14 and the upper housing 15 is not limited to it, and the housings may be jointed by other structures.

[0024] In the following description, a housing applied to an electronic apparatus such as the portable computer 10 will be explained as an electronic apparatus housing 20, and a method of manufacturing an electronic apparatus using the electronic apparatus housing 20 will also be explained. Further, the method of manufacturing the electronic apparatus is shown in FIG. 3, and the process will also be described.

[0025] The electronic apparatus housing 20 shown in FIG. 4, which is used for an electronic apparatus such as personal computer and formed of a light metal made of a magnesium alloy has boss portions 21 in order to mount an electronic circuit and other various parts inside. In the electronic apparatus housing 20, in order to form the boss portions 21, the electronic apparatus housing 20 is formed by the following steps.

[0026] Specifically, a mold device 30 used in FIG. 6 is used in order to form the electronic apparatus housing 20. The mold device 30 comprises an upper mold 31 and a lower mold 32, and the mold device 30 is formed by engaging these molds. The mold device 30 is provided with a sprue 33 which is an introducing port of molten metal, and a runner 34 which guides molten metal from the sprue 33 into a cavity 35 of the mold device 30 so that the molten metal is uniformly diffused. The molten metal guided by the runner 34 is introduced into the cavity 35 of the mold device 30.

[0027] The molten metal is a molten magnesium alloy. In addition to this, a molten metal of a molten aluminum alloy can be used, for example.

[0028] In the cavity 35, in order to form boss portions 21 projecting from a bottom surface of the above electronic apparatus housing 20, the internal wall surface of the cavity 35 is hollowed by a predetermined diameter to form hole portions 36. Although the hole portions 36 do not have a height necessary as the boss portions 21, the depth of the hole portions 36 are set so as to form projecting portions 22 having a height to reach a halfway portion of the boss portions 21.

[0029] Specifically, in the case where a molten metal of magnesium alloy is used, when the diameter of the projecting portions 22 is d and the height of the projecting portions 22 is h as shown in FIG. 5, they are provided so as to fall within the range of h/d= 1.5-2.0.

[0030] The molten metal filled into the cavity 35 reaches an air vent 37 provided on the other end side of the cavity 35. The air vent 37 is aimed at releasing air existing in the cavity 35 from the inside of the cavity 35 to the outside. Thereby, the molten metal introduced into the cavity 35 reaches a basin 38 while generation of void in the cavity 35 is prevented.

[0031] The molten metal is introduced into the cavity 35 by injection molding so that the molten metal instantly reaches the above air vent 37. When the molten metal reaches the air vent 37, since the temperature of the mold device 30 is low, that is, about 100-350°, the solidification of the molten metal as a molded product 40 is started immediately in a part of the internal wall surface of the mold device 30 with which the molten metal is brought in contact (a housing forming step).

[0032] After the molded product 40 has been formed, the molded product 40 is taken out from the mold device 30. Then, a screw hole 23 serving as a female screw is formed at each projecting portion 22, and a boss separate body 24 formed as a separate piece is engaged in the screw hole 23 (a boss-portion forming step). The boss separate body 24 is formed of metal, and has a structure for conducting charged electricity to the molded product 40 when an electric circuit 41 or the like mounted on the upper end side of the boss separate body 24 is charged.

[0033] As shown in FIG. 5, in order to make it possible to mount the boss separate body 24 by screw engagement, the boss separate body 24 is provided with a screw portion 26 which is formed with a smaller diameter to project from a main body 25 of the boss separate body 24 so as to correspond to the screw hole 23 formed at the projecting portion 22. Specifically, the boss separate body 24 has a structure wherein the screw portion 26 is formed with a smaller diameter to project from the main body 25 of the boss separate body 24.

[0034] A screw groove serving as a male screw is formed on an external surface of the screw portion 26. The screw groove is engaged with the screw hole 23, and thereby the boss separate body 24 is fixed to the projecting portion 22 by screw engagement.

[0035] Further, an external diameter of the boss separate body 24 is formed to be almost equivalent to that of the projecting portion 22. Thereby, the external diameter of the boss portion 21 is made uniform.

[0036] An engaging hole 27 for engaging another member is formed in the boss separate body 24 downward from the upper end of the boss separate body 24. The engaging hole 27 is provided for mounting and fixing the electronic circuit 41 and other various parts which are separated from the electronic apparatus housing 20.

[0037] Specifically, the boss portion 21 is formed by forming the screw hole 23 at the projecting portion 22 of the molded product 40, further providing the boss separate body 24 and forming a screw groove on the screw portion 26, and engaging the boss separate body 24 in the screw hole 23.

[0038] Thereby, an electronic circuit or other various parts can be fixedly engaged in the engaging hole 27 located in the boss portion 21 via a screw and bolt.

[0039] According to the electronic apparatus housing 20 and the method of manufacturing the electronic apparatus housing 20 having the structure as described above, in the mold device 30, the hole portions 36 are formed to project to conform to the projecting portions 22, and the molded product 40 is formed by introducing the molten metal into the hole portions 36. Therefore, if the height of the projecting portions 22 is made low, that is, if the depth of the hole portions 36 of the mold device 30 is made shallow, it is possible to flow the molten metal into the hole portions 36 in a good state.

[0040] Specifically, when the molten metal is introduced into the cavity 35, in particular, in the case where the diameter of the projecting portions 22 is d and the height thereof is h, by setting d and h within the range of h/d=1.5-2.0, it is possible to fill the molten metal into the hole portions earlier than start of solidification of the molten metal.

[0041] Therefore, even in the case of using a molten metal of magnesium alloy having a low flowability, whose flowability is apt to deteriorate when it comes into contact with a low-temperature part inside the cavity 35, it is possible to fill the molten metal in a good state into the end portion side of the hole portions 36. Thereby, no non-filled portion is generated in the hole portions 36, and it is possible to form the projecting portions 22 in a good state.

[0042] Further, since the apparatus has the structure wherein the boss separate body 24 is separately fixed by screw engagement to the projecting portion 22 whose height is reduced, if the height of the boss separate body 24 is set appropriately, it is possible to set the boss portions 21 to a desired height.

[0043] Furthermore, since the boss separate body 24 is formed of metal, even if the electronic circuit 41 or the like is mounted on the upper end side of the boss separate body 24, the electronic circuit 41 or the like is not charged with static electricity and the static electricity is introduced into the molded product 40 through the boss separate body 24. Specifically, the electronic circuit 41 or the like is earthed.

[0044] Thereby, it is possible to prevent break of the electronic circuit 41 or the like due to flowing of a large current into the electronic circuit 41 or the like by short circuit.

[0045] Further, since the apparatus has the structure wherein the projecting portions 22 are formed and the boss separate bodies 24 are fixed to the projecting portions 22 by screw engagement, there is no inconvenience that screw threads project from a lower surface of the thin molded product 40, in comparison with the case where the boss separate bodies 24 are mounted on a part where projecting portions 22 are not formed. Therefore, in the case where a personal computer or the like is placed with its lower surface positioned at the bottom, it is possible to improve the stability in placement. Further, in order to improve the stability in placement, there is no need to form hollows for receiving head portions of bolts.

[0046] Although the embodiment of the present invention has been described above, in addition to the above, the present invention can be modified in various ways as described below.

[0047] Although in the above embodiment the boss separate bodies 24 are engaged with the projecting portions 22, the boss separate bodies 24 may also be mounted on the projecting portions 22 by means of press fitting or caulking, for example.

[0048] Further, the apparatus may have a structure wherein the screw portion 26 provided on the boss separate body 24 and the screw hole 23 are provided vice versa. Specifically, the lower end of each boss separate body 24 is formed to have a larger diameter and a screw hole is formed in the portion, and each projecting portion is formed to have a smaller diameter and a screw thread is formed on the external surface of the projecting portion 22 to form a screw portion.

[0049] Further, other various modifications are possible within the range which does not change the gist of the present invention.

[0050] Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

1. An electronic apparatus comprising: a housing formed as one piece with a first boss member; and a second boss member formed as a separate piece from said first boss member, and mounted on said housing to form a boss portion.
 2. An electronic apparatus comprising: a housing having a projecting portion formed as one piece therewith; and a boss member to be mounted on said projecting portion to form a boss portion.
 3. An electronic apparatus according to claim 2 , wherein said second boss member is fixed to said projecting portion by screw engagement.
 4. An electronic apparatus according to claim 2 , wherein a height of projection of said projecting portions from said housing is within a range of approximately 1.5-2.0 times an external diameter of the projecting portions.
 5. An electronic apparatus according to claim 1 , wherein said housing is formed of a magnesium alloy, and said boss members are formed of metal.
 6. A method of manufacturing an electronic apparatus having a housing with a boss portion, comprising the steps of: a housing forming step for forming the housing introducing molten metal into a mold device, the housing having a projecting portion at a location where said boss portion is to be formed, and the housing constituting portions other than the boss portion of said housing; and a boss portion forming step for forming the boss portion by fixedly engaging a boss member, which is to constitute the boss portion, with said projecting portion. 